Conventionally, oil circulates inside a cylinder head, a cylinder body, a crankcase and so forth in an engine for a motorcycle. The cylinder head is provided with an intake valve and an exhaust valve. A cam chamber formed along a cylinder head and a cylinder head cover is provided with a camshaft equipped with a cam for driving the intake valve and the exhaust valve. The camshaft is connected to a crankshaft through a cam chain. The camshaft rotates driven by the rotation of the crankshaft. The cam chain and a chain guide for guiding the cam chain are disposed in a cam chain chamber formed along the cylinder head cover, the cylinder head and so forth.
A sufficient amount of oil needs to be supplied to the cam chain to effectively transmit a driving force of the crankshaft to the cam shaft, and to prevent the wear of the chain guide that comes in contact with the cam chain. Japanese examined utility model application publication No. 64-3764 discloses an engine having a projection formed on a cylinder head cover above a chain guide. The oil scattered by the rotation of a cam chain comes in contact with the projection, drops onto the chain guide, and is then supplied to the cam chain.